MEXICO CITY (Reuters) - Mexican rescue workers found three more bodies over the weekend amid the rubble of a deadly blast that tore through state oil firm Pemex's main office complex, the government said, as search efforts appeared to near a close.

Rescue workers carry a stretcher with the body of the 36th victim at the site of an explosion at the headquarters of state-owned oil giant Pemex in Mexico City February 3, 2013. REUTERS/Stringer

The death toll from Thursday's explosion stands at 36, Pemex said via Twitter. Rescue workers had been digging through the last sections of the building's basement and could soon call off their search. One person was reported still missing.

Attorney General Jesus Murillo said on Friday that it was too early to say if the explosion was due to an attack, an accident or negligence, but he promised results of an investigation in the coming days.

Murillo toured the site on Sunday, but did not publicly comment on the progress of the investigation. Officials have communicated details through social media about the disaster, which struck just before a long holiday weekend.

The investigation will test confidence in President Enrique Pena Nieto, whose Institutional Revolutionary Party ruled Mexico for most of the last century but lost power in 2000, when it was accused of fostering widespread corruption.

Local media reported the three bodies were maintenance workers. A woman who worked as a secretary was still missing, but she was unlikely to be found so deep in the wreckage.

The blast occurred two months into Pena Nieto's presidency, just as Congress was preparing to discuss his plans to open up the state-run energy industry to more private investment.

Hobbled by heavy state taxation, Pemex saw production slump in the last decade and its safety record has been stained by a series of deadly accidents, including an explosion that killed about 30 at a gas facility last year.

• Malaysia tycoon Vincent Tan plans IPO of football club Cardiff City
• Google, like Facebook, in talks to buy Waze for about US$1bil
• Crown selling entire 10% in rival Echo, partly owned by Genting(Update)
• First edition of 'Great Gatsby' to be sold at auction, can fetch US$150,000
• Malaysia leads the way in Basel III debt
• Markets face rough summer ride as Fed pullback feared
• Wall Street sags, HP hits 52-week high
• Commodities trader sues BP, Shell others for alleged oil price fixing
• Billionaire Icahn seeks up to US$7bil for Dell bid
• Google faces new federal antitrust probe
• Goldman Sachs unveils checks on conflicts in bid to fix tarnished image
• Air Asia's Tony Fernandes to ‘fire up’ investors
• Maybank bullish on growth, to expand regionally under new leadership
• Khazanah appoints Nor Mohamed deputy chairman
• Lafarge Malayan Cement to finalise next expansion plans by August

• British police arrest two men on diverted Pakistan flight (Updated)
• Britain scrambles fighter jets to escort Pakistani passenger plane
• 5,000 cave paintings discovered in Mexico
• Cars, schools ablaze in fifth night of Stockholm riots
• London's Heathrow airport closed after emergency landing
• Far East quake felt in Moscow, tsunami warning lifted
• Police make new arrests in London soldier killing
• Britain's press demands jailing of Islamist preacher
• Tsunami warning in Russia's Far East after 8.2 quake
• US bridge collapse sends cars, people into river
• Strong quake strikes off Tonga
• Jury fails to decide on US murderer death sentence
• One killed in Brazil giant fuel depot blaze

• British Open: Nicol David deals with disruptions for semi spot
• Kingston leads, McIlroy in Wentworth woe
• LPGA plans 12-hole rounds in water-logged Bahamas
• Ryan Palmer sizzles with 62 to seize lead at Colonial
• Kelly overcomes scare to clinch title in KLGCC
• Time to make amends Garcia wants to meet Woods to defuse racist row
• American Johnson back to defend Colonial crown
• Rain dampens debut of LPGA Bahamas event
• Tianlang adds another US event to schedule
• Clock ticking for next golden generation
• Nadal wants to create history at Roland Garros
• Serena out to tame French Open demons
• Zheng Jie stuns Wozniacki in Brussels
• British Open: Ramy Ashour racks up 38th successive win
• Nicol David sails into quarter-finals of British Open in 35 minutes

• Please wait.

• KL car number plates to bear ‘W1A’
• Air Asia's Tony Fernandes to ‘fire up’ investors
• Singapore GDP growth surprises, beats economists’ forecast of contraction
• Tian, Tamrin and Haris released after remand denied (updated)
• Malaysia leads the way in Basel III debt
• Inventions a-plenty, but no real innovation
• Robber shot dead after attacking out-of-uniform cop with meat cleaver
• Thousands throng thanksgiving rally by DAP
• EC: Photograph of ‘blackout’ on polling day was a lie
• Lafarge Malayan Cement to finalise next expansion plans by August